There exists a need to cover dressings, wraps, casts and other bandages for aesthetic reasons and to protect them from soil and moisture. To this end, there are numerous simple coverings in common use which afford some degree of protection. Among the most common of these is a tubular knit sock which is pulled over the cast or wound dressing, and the common elastic bandage which is wrapped around the cast or wound dressing. While such coverings are suitable to protect the dressing from soil, they are inadequate to protect the dressing from water, since they are easily wetted.
A number of cast covers are known which are useful in reducing the wetting of a cast during bathing or other exposure to water. U.S. Pat. No. 4,523,586 discloses a loose fitting bag made of flexible material and adapted to fit over a cast and be sealed with fasteners around the casted limb. The cast is thus protected from water damage. Similarly, U.S. Pat. No, 4,346,699 discloses a balloon-like cast cover into which the casted limb is inserted and the neck of which is adapted to fit tightly about the casted limb above the cast. While these cast covers are impermeable to water, their usefulness is limited to short term exposure to water such as occurs during bathing. They are not suitable for extended wear because the escape of water vapor from the inside of the cast cover is prevented or impeded, evaporative cooling of the skin under the cast or dressing is prevented, and discomfort to the user results.
Disclosed in U.S. Pat. No. 4,552,795 is a heat-shrinkable sheet material formed by stretching elastomeric strands and then bonding them to one or more flat inelastic webs. When the sheet material is heated, the strands contract, the material shirrs, and an elastic laminate results. The flat inelastic webs may be porous and nonwoven, and a porous elastic wrap suitable for holding bandages in place is taught.
U.S. Pat. No. 3,329,143 discloses a tubular cast cover of highly plasticized heat-shrinkable polyvinyl chloride homopolymer or copolymer. The cover is adapted to thermally shrink to closely fit the contours of a cast upon exposure to temperatures of 60.degree. C. to 82.degree. C. Further, the cover is perforated to allow air and water permeability, although no method of perforation is described. This cast cover appears to be weak and easily torn, thus requiring frequent replacement by the user. Furthermore, the air and water permeability achieved by physical perforation of the covering may be inadequate since the permeability is not continuous throughout the covering and water may penetrate the covering through the holes and wet the cast.